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    Energy-Saving Non-Metallic Connectors for Precast Sandwich Wall Systems in Cold Regions
    (North Dakota State University, 2014) Allard, Austin
    Conserving energy in large structural buildings has become very important in today's economy. A number of buildings today are constructed with sandwich wall panels. Steel connections are most commonly used in these panels. The problem with steel is that it has a tendency to reduce the thermal resistance of the insulation. This project considers glass fiber reinforcing polymers (GFRP) and carbon fiber reinforcing polymers (CFRP) as an alternate material to steel. An experimental sandwich wall panel was constructed and subjected to freezing temperatures. The results of the experimental program were compared to a theoretical model using the ANSYS computer program. The model was verified using current analytical methods that determine the heat flux of a sandwich wall panel. The methods investigated include the parallel path, zone, parallel flow, and isothermal planes methods. The results suggest that the GFRP connectors perform slightly better than the steel and CFRP connectors.
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    Time-dependent Behavior of Various FRP Composites for Structural Applications
    (North Dakota State University, 2011) Khan, Md. Fuad Hassan
    This thesis represents the long-term behavior of fiber reinforced polymer (FRP) materials for structural applications. FRP composites consist of high-strength fibers embedded in an epoxy resin. The long-term investigations include i) pultruded glass FRP (GFRP) beams subjected to sustained loads and cold temperature and ii) reinforced concrete beams strengthened with near-surface mounted (NSM) carbon FRP (CFRP) strips. For the first phase, test parameters include the variation of sustained intensities and temperature. The flexural behavior of the long-term beams is studied through a combined experimental and numerical approach, including load-carrying capacity, failure mode, creep response, and material degradation. Some material parameters that are crucial for practical applications are suggested using a regression analysis. A finite element model is developed to predict the behavior of GFRP beams. An analytical model is also proposed to estimate the long-term behavior of GFRP composites for structural applications. For the second phase, test parameters include the variation of sustained intensities, CFRP strengthening schemes and bonding agents. The short-term beams are loaded both monotonically and cyclically whereas the long-term beams are loaded only monotonically. The flexural behavior of all beams is studied through an experimental investigation, including load-carrying capacity, failure mode, creep response, and material degradation.